1. Field of the Invention
The present invention relates to a method and an apparatus for developing an electrophotographic master plate for printing, and more particularly to a method of developing an electrophotographic master plate for printing having an insulating support member on which a conductive layer and a photoconductive layer are laminated and a developing apparatus for performing the developing method.
2. Description of the Related Art
A planographic printing plate for use in an electrophotographic method is manufactured by a wet electrophotographic plate making machine structured as disclosed in Unexamined Japanese Patent Publication (kokai) No. 10-260597. The outline of the foregoing machine will now be described. An electrophotographic master plate for printing (hereinafter simply abbreviated as a "master") is conveyed to an electrifying portion to uniformly electrify the electrophotographic master plate for printing by virtue of corona discharge. Then, the electrophotographic master plate for printing is conveyed to an exposing portion to expose an image (an original document) to light. The master having the exposed image is conveyed to a developing apparatus also called a liquid-toner developing portion.
The wet electrophotographic developing apparatus is arranged to convey the master into toner developer enclosed between a pair of electrodes usually composed of a back plate (an electrode adjacent to a support member) and developing plate (an electrode adjacent to the surface which must be developed). Thus, toner development is performed in the toner developer. An example of a modification of the wet electrophotographic developing apparatus has been'disclosed in Unexamined Japanese Patent Publication (kokai) No. 9-96956. The foregoing apparatus is arranged to apply voltage to the pair of the electrodes during conveyance to form a toner image also using the foregoing function realized by the developer. The master incorporates a support member, such as paper to which conductivity has been imparted, and a photoconductive layer formed on the support member.
A portion of the masters incorporates the support member made of paper or the like and a photoconductive layer formed on the support member. The foregoing structure encounters irregularity in the density caused from states of tangling of pulp constituting the paper. Hence it follows that microscopic asperities are formed on the surface and, therefore, the flatness deteriorates. Moreover, permeability of coating solution encounters irregularity. Thus, the image quality deteriorates. Therefore, if the toner image is fixed as described above, improvement in the image quality has been limited.
To overcome the above-mentioned problems, it might be considered feasible to employ a resin sheet having flatness superior to that of the paper. The resin sheet, however, has no conductivity. Therefore, the resin sheet cannot be employed as the master which is developed by the electrophotographic developing apparatus.